Heat exchanger



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Car '/f' A TTRNE YS United States Patent C) HEAT EXCHANGER Roy R.Graves, Valparaiso, Ind., assignor to The Graves- Stambaugh Corporation,a corporation of Delaware Applicatie April 2s, 1951, serial No. 223,483

2 canins. (ci. 257-246) This invention relates to heat exchangers andthis application is a continuation-in-part of my copending applicationSerial No. 742,673 filed April 19, 1947, now abandoned.

The principal object of this invention is to provide an improved heatexchanger which is extremely rapid and ecient in operation, which issimple and compact in construction, which is relatively inexpensive tomanufacture, which may be readily disassembled for cleaning purposes,and which is particularly adaptable for use in the food industry forpasteurizing, sterilizing or cooling milk, fruit or vegetable juices orthe like.

In this respect the heat exchanger comprises a substantially cylindricalhollow casing having an enclosed heat exchange chamber therein andhaving a smooth and slightly and uniformly tapered inner surfaceextending from end to end, and also a substantially cylindrical corelongitudinally removably received in the casing, having an enclosed heatexchange chamber therein and having a slightly and uniformly taperedouter surface extending from end to end conforming to the taper of theinner surface of the casing to provide a tight seal between the casingand the core throughout their lengths when the core is received in thecasing. A spiral groove is provided in the outer tapered surface of thecore to form in conjunction with the casing a spiral passage throughwhich the product to be heated or cooled is circulated.

A ring is removably and longitudinally adjustably carried by the casingand engages the end of the core for forcing the tapered outer surface ofthe core into sealing engagement with the tapered inner surface of thecasing. When the ring is removed, the core may be longitudinally removedfrom the casing to expose the grooved external surface of the core andthe smooth internal surface of the sleeve so that said surfaces may bereadily cleaned.

The casing is preferably formed from two sleeve members or tubes whichare secured together in spaced relation to form the enclosed heatexchange chamber therebetween, the inner sleeve member or tube havingthe smooth and slightly and uniformly tapered inner surface. The corealso preferably includes an outer sleeve member or tube which providesthe slightly and uniformly tapered outer surface on the core. Theenclosed heat exchange chamber in the core may be formed by the outersleeve member and end plugs cooperating therewith or by the outer sleevemember and an inner sleeve member or tube secured thereto in spacedrelation.

Inlet and outlet ports communicate with the enclosed heat exchangechambers for circulating a heat exchange medium, such as steam, water orthe like, therethrough. Inlet and outlet ports for the product to beheated or cooled extend through the casing and open into the taperedinner surface of the internal sleeve of the casing near opposite ends ofthe casing. These inlet and outlet ports register with the ends of thespiral groove in the tapered outer surface of the core to provide astraight through passage for the product to be heated or cooled. Thiseliminates pockets in which the product might be trapped and this is ofgreat importance in the case of a heater, pasteurizer or sterilizerwhere the product would become overheated in such pockets.

Further objects of this invention reside in the details of constructionof the heat exchanger and in the cooperative relationship between thecomponent parts thereof.

Other objects and advantages of this invention will become apparent tothose skilled in the art upon ref- 2,706,620 Patented Apr. 19, 1955erence to the accompanying specification, claims and drawings, in which:

Fig. 1 is a side elevational view of one form of the heat exchanger;

Fig. 2 is a vertical sectional view of the heat exchanger of Fig. 1;

Fig. 3 is a vertical sectional view taken substantially along the line3--3 of Fig. 2;

Fig. 4 is a sectional view of a support for the sleeve nerlriber ortubes forming the casing in the heat exchanger o 1g.

Fig. 5 is a sectional view of a secondary head utilized in the core ofthe heat exchanger of Fig. 1;

Fig. 6 is a sectional view of the outer sleeve member or tube of thecore and the inner sleeve member or tube of the casing showing theslight tapered joint between these sleeve members;

Fig. 7 is an enlarged sectional view showing a modified form of thespiral groove in the outer surface of the core;

Fig. 8 is a diagrammatic view of an installation of heat exchangers in amilk storage and bottling system of a new type of dairying equipment;

Fig. 9 is atop plan view of a heater and cooler assembly utilizing twoheat exchangers of a construction different from the heat exchangersillustrated in Figs. 1 to 7;

Fig. 10 is a side elevational View of the heater and cooler assembly ofFig. 1 showing the core of the cooler raised above the casing forcleaning purposes;

Fig. 1l is a vertical sectional view of the heater taken substantiallyalong the line 11-11 of Fig. 10;

Fig. 12 is a vertical sectional view of the cooler taken substantiallyalong the line 12-12 of Fig. 9;

Figs. 13 and 14 are diagrammatic top plan views of the heater and coolerof Figs. 11 and 12 illustrating the relative positions of the variousinlet and outlet ports;

Fig. 15 is a horizontal sectional view taken substantially along theline 15-15 of Fig. l0; and

Fig. 16 is a side elevational view partly in section of a casing for aheater provided with thermal insulation.

Referring lirst to the forms of the invention illustrated in Figs. l to8 there is disclosed a heat exchanger having a substantially cylindricalcasing and a substantially cylindrical core longitudinally removablyreceived in the casing. The casing includes an outer sleeve member ortube 1 and an inner sleeve member or tube 2. The inner surface 29 of theinner sleeve member or tube 2 is smooth and is slightly and uniformlytapered from end to end, the taper being of approximately 1.25% or less.The sleeve members 1 and 2 are secured together in spaced relation byheads or rings 4 and 5. The heads or rings 4 and 5 are provided withannular shoulders 38 and 39 for receiving the ends of the outer sleevemember 1, the sleeve member being secured to the heads or rings 4 and 5as by welding, indicated at 22 and 23. The inner sleeve member 2 issecured to the heads or rings 4 and 5 as by welding, indicated at 24 and26. There is thus provided between the sleeve members 1 and 2 anenclosed heat exchange chamber 12. The heat exchange iiuid in the formof steam, water or the like, enters the heat exchange chamber 12 throughan inlet pipe 14, suitably secured in the outer sleeve member 1. Theheat exchange iiuid is discharged from the heat exchange chamber 12through an outlet pipe 15, also carried by the outer sleeve member 1. Inthis way heat exchange fluid is circulated through the heat exchangechamber 12.

The core includes an outer sleeve member or tube 3 having its outersurface slightly and uniformly tapered from end to end to conform to thetaper of the inner surface of the sleeve member 2 of the casing toprovide a tight seal between the casing and the core throughout theirlengths when the core is received in the casing. One end of the sleevemember 3 is secured to a head or disc 37 as by welding, indicated at 2S.The other end of the sleeve member 3 engages a shoulder 40 of a head 7and is suitably secured to the head 7, as by means of welding. The heads37 and 7, along with the sleeve member 3, form an enclosed heat exchangechamber 13 through which a heat exchange medium, such as steam, water orthe like, is circulated. The outer surface of the sleeve member 3 of thecore is provided with a spiral or helical groove 21, the convolutions ofwhich are separated or divided by partition walls 36. When the core isreceived in the casing the spiral groove 21, in conjunction with thesleeve member 2, form a spiral passage through which the product to beheated or cooled flows.

The product to be heated or cooled enters the heat exchanger through aninlet pipe and discharges therefrom through an outlet pipe 11 aftercoursing the spiral passage 21. The inlet pipe 10 extends through theouter sleeve member 1 and through the inner sleeve member 2 to provide aport which opens into the tapered inner surface of the internal sleevemember 2 in registry with one end of the spiral groove 21. The pipe 10may be threaded into inner sleeve member 2 and secured to the outersleeve member 1 as by welding, indicated at 27. The outlet pipe 11likewise extends through the outer sleeve member 1 and the inner sleevemember 2 and opens into the tapered inner surface of the internal sleevemember 2 in registry with the other end of the spiral groove 21. Thisoutlet pipe 11 may also be screw-threadedly received in the internalsleeve member 2 and welded to the outer sleeve member 1, as indicated at28.

A head 6 operates to pack or seal the joint between the casing and thecore and in this respect, the head 6 is provided with a conical ortapered surface 30 for engaging a conical or tapered surface on the endof the inner sleeve member 2 of the casing. The head 6 has an annularflange lying adjacent the head or ring 4 and a ring or sleeve 8 isscrew-threadedly carried at 32 by the head 4. When the ring or sleeve 8is drawn up tight, the conical surface 30 of the head 6 engages theconical end of the tube 2 to pack or seal the joint between the casingand the core.

The head or ring 5 is provided with an internal flange 43 and an innersurface 44. Gaskets 31 are received by the inner surface 44 and abut theflange 43 of the head 5 and also abut the ange 41 of the head 7. Aflanged sleeve 9 is screw-threadedly carried at 33 by the head 5, theange of the sleeve engaging the head 7. As the anged sleeve 9 istightened the core is forced into the casing and the gaskets 31 arecompressed. In this way a tight seal is established between the twosleeve members 2 and 3 throughout their lengths and the end of the jointbetween the two sleeve members is packed against any possible leakage.

Heat exchange medium is supplied to the inner enclosed heat exchangechamber 13 by means of an inlet pipe 16 carried by the head or ring 5.This inlet pipe communicates through a port 19 in the heads 5 and 7 witha pipe 17 screw-threadedly carried by the head 7, as indicated at 35,and extending longitudinally into the heat exchange chamber 13. Theinner end of the pipe 17 is open, as indicated at 34, so that heatexchange medium is supplied to one end of the heat exchange chamber 13.Heat exchange medium is discharged from the heat exchange chamber 13 bymeans of an outlet pipe 18, also carried by the head or ring 5. Theoutlet pipe 18 communicates through a port 20 in the heads 5 and 7 and aport 34 in the head 7 opening into the heat exchange chamber 13.

By removing the anged sleeve or ring 9 the core may be withdrawn fromthe casing to expose the inner smooth tapered surface of the casing andthe outer grooved tapered surface of the core to facilitate cleaning ofthese surfaces. If desired, the head 6 may also be removed by removingthe ring or sleeve 8, further to facilitate cleaning of the casing. Toreassemble the heat exchanger the core is inserted into the casing andthe anged sleeve or ring 9 is drawn up tight. When this is done a tightseal is established throughout the lengths of the core and sleeve andthe ends of the joint between the core and sleeve are sealed. In orderto register the ends of the spiral or helical groove 21 with the inletand outlet pipes 10 and 11 and to register the ports 19 and 20 when thecore is inserted into the casing, the ends of the casing and core may beprovided with suitable spotting points. Should the seal between the coreand the casing stick when the core is to be removed from the casing,then they may be quickly separated by circulating steam through theouter heat exchange chamber 12 and cold water through the inner heatexchange chamber 13. This will cause a differential expansion betweenthe core and the casing readily to separate the joint between the casingand the core. In order to provide maximum turbulence in the productflowing through the helical or spiral groove, the center of the groove,as shown in Fig. 7, may be provided with an upstanding projection 32.Screw-threads 58 or the like may be formed on the outer surface of theinner tube 2 of the casing, as illustrated in Figs. 6 and 7, in order toincrease the contact area between this tube and the heat exchange mediumin the heat exchange chamber 12.

Heretofore in the production of heat exchangers it has been the customto make the parts of cast metal. In accordance with this invention,however, I prefer to use standard dimension stainless steel tubing forforming the sleeve members 1, 2 and 3. The outer surface of the sleevemember 3 of the core, as shown in Fig. 6, is gradually decreased ortapered from end to end leaving the inside diameter at its standarddimension. Likewise, the inner sleeve member 2 of the casing retains itsstandard outside diameter but the inside diameter is tapered tocorrespond to the outside diameter of the core. This slight taper 29, ofapproximately 1.25% or less, permits the use of the standard dimensiontubing and also insures continuous contact between the two engagingsurfaces and avoids the possibility of leakage between adjacentconvolutions of the helical or spiral groove 21 across the ridge orpartition 36. While in Figs. l to 7 the heat exchanger has been shown inhorizontal position, it may be positioned vertically with the right-handend of Fig. 2 at the top.

While the heat exchanger, disclosed above, is of general utility, it hasparticular utility for pasteurizing, sterilizing or cooling food stuffs,such as milk, fruit or vegetable juices or the like, and may beadvantageously utilized in the dairying system, diagrammaticallyillustrated in Fig. 8. This dairying system includes a vacuum receivingtank 45 in which milk that comes from milking machines is stored. Themilk is drawn from the receiving tank 45 into a homogenizer 46 whichalso functions as a pump. The milk` 1s pumped into a pasteurizing unit47 and then a holding tube or valve 48 and then passes a diversion valve49 if the temperature of the milk at the exit of the holding tube 48 isup to 162 degrees F. lf the milk is not up to that temperature, it isdiverted back through pipe 51 to the pasteurizing unit 47. However, ifit is up to that temperature it passes the diversion valve 49 and entersa second unit 50 for water cooling the milk. It may also pass through athird unit 52 for cooling the milk to a lower temperature. The dairyingsystem may also include a bottle lling machine having a vacuum tank 53for receiving the milk to be bottled. The milk passes from the vacuumtank 53 under the control of a valve 54 for filling bottles 55 undervacuum. The capper 56 caps thebottles after lling and a revolving feedermay be utilized to maintain the vacuum in the chamber where the bottlesare being lled and capped.

When the heat exchanger is utilized as the pasteurizer 47, steam or hotwater may be utilized as the heat exchange medium. When the heatexchanger is used as the rst cooler 50, the heat exchange medium may bein the form of tap water and when the heat exchanger is. used as thesecond cooler 52, the heat exchange medium may be a refrigerating agent,such as sweet water, brine or the like.

In the pasteurization unit 47 the steam or hot water in the heatexchange chambers 12 and 13 cooperates in producing the necessary heatfor raising the temperature of the milk to 162 degrees F. In theinstallation illustrated in Fig. 8, the milk will not have been cooledafter being drawn from the cows until it is pasteurized. Its temperaturewill be approximately degrees F. as the milk enters the pasteurizer 47.As a result, the milk will need to be raised only from 95 to 162 degreesF. instead of from 40 or 5() degrees F. to 162 degrees F., which wouldhave been required if the milk had previously been cooled. When steam isused as the heating agent its pressure is controlled to the properpasteurization temperature. In the event that water is used as theheating agent, its temperature is controlled by use of suitablethermostatic control and it may be circulated through the pasteurizer bymeans of pumps operating at the required pressure. This insures that themilk will be raised to the proper temperature. The rate at which themilk ows through the pasteurizing unit 47 under a pressure of 30 poundsper square inch is approximately 2.3 gallons per minute. With the rateof flow of milk controlled and the entering temperature of the milksubstantially established and with the heating medium temperature andpressure under control, the end temperature of the milk may be veryclosely controlled in this type of enclosed pasteurizer. Since the milkis subjected to applied heat on all sides While it undergoes turbulencein its spiral flow around the core, all particles of the milk are actedupon and the highest efficiency is secured.

The heat exchange unit or cooler 50 is used to reduce the temperature ofthe pasteurized milk from 162 degrees F. to a point as near as possibleto that of tap or well water. This water is circulated through the heatexchange chambers 12 and 13 in a similar manner as the heating agentduring pasteurization. The temperature of the milk at the outlet of thiscooler unit 50 will be less than 10 degrees above the water that isbeing used for cooling purposes for the reason that the milk is actedupon on all sides by the cooling agent and has relatively greatturbulence in its flow through the helical groove of small cross sectionarea. The third unit or cooler 52 is used to lower the temperature ofthe milk to approximately 35 degrees F. before bottling. It may utilizeas the cooling medium sweet water or brine which is cooled by anydesired method of refrigeration and which is circulated through the heatexchange chambers 12 and 13. If desired, the cooling may be accomplishedby a direct expansion method of refrigeration, the refrigerating gasesbeing circulated through the heat exchange chambers 12 and 13. In anyevent, the refrigerating agent is circulated through the heat exchangechambers in substantially the same manner as the steam or hot water iscirculated through the pasteurizing unit.

It is common in all high temperature pasteurization practices to holdpasteurization temperatures for short time periods. Health authoritiesrequire that in the high temperature short time pasteurization of milk,the temperature of the milk must be held at the 162 degree F. level forl seconds. Such short time periods are under the control of thediversion valve which will return any part of the milk that is not atthe required temperature back to the initial pasteurizing unit. Aself-recording thermometer may be used to indicate continuously theoperating temperatures. These expedients shown diagrammatically in Fig.8 cooperate with the heat exchangers of this invention to form acomplete milk handling system.

Figs. 9 to 16 illustrate further forms of the heat exchanger` of thisinvention, which likewise are of general utility but which areparticularly useful in processing food stuffs. In Figs. 9 and 10 thereis disclosed a heater and cooler assembly including a heater generallydesignated at 110, a cooler generally designated at 111 and a supportingstand for the heater and cooler generally designated at 112. This heaterand cooler assembly is particularly useful for pasteurizing orsterilizing milk, fruit or vegetable juices or the like, the heater 110doing the pasteurizing or sterilizing and the cooler 111 doing thecooling.

The heater 110 is illustrated in more detail in Figs. 11 and 13. Theheater includes a substantially cylindrical casing having an outersleeve member or tube 114 which is secured, as by welding, to flanges115 on an inner sleeve member or tube 116. The inner surface 117 of theinner sleeve member 116 is smooth and slightly and uniformly taperedfrom end to end. The wider portion of the tapered inner surface 117 islocated uppermost. The flanges 115 space apart the outer and innersleeve members 114 and 116 to form therebetween an enclosed heatexchange chamber 118.

A fitting 119, having a hole 121 communicating with the enclosed heatexchange chamber 118, is secured, as by welding, to the outer sleevemember 114 near the top thereof for delivering steam, hot water or thelike to the heat exchange chamber 118. Likewise, a fitting 120, having ahole 122 communicating with the heat exchange chamber 118, is secured,as by welding, to the outer sleeve member 114 near the bottom thereoffor discharging steam or water from the heat exchange chamber 118. Inthis way heat exchange uid, such as steam or water, may be circulatedthrough the heat exchange chamber 118 in the casing. A supporting ring123 is secured to the bottom of the casing, as by welding, and,likewise, another ring 124 is similarly secured to the top of thecasing. A fitting 125 is secured to the casing, as by welding, and itextends through the flange portion 115 of the casing and opens into thetapered inner surface 117 of the internal sleeve 116 near the bottomthereof. Another fitting 126, likewise, is secured to the casing andextends through the flange portion 115 and opens into the tapered innersurface 117 of the internal sleeve 116 near the top of the casing. Thefittings and 126 form inlet and outlet ports for the product to beheated as, for example, the milk or juices to be pasteurized orsterilized.

The heater also includes a substantially cylindrical core which islongitudinally removably received in the casing. The core may bevertically inserted into the casing and vertically raised therefrom. Thecore includes an inner sleeve member or tube 128 which is provided atits ends with flanges 129 to which is secured, as by welding, an outersleeve member or tube 130. The outer surface of the external sleevemember 130 of the core is slightly and uniformly tapered from end to endand conforms to the taper of the internal sleeve member 116 of thecasing. When the core is inserted in the casing a tight seal isestablished between the two sleeve members 116 and 130 throughout theirlengths. The outer tapered surface of the sleeve member 130 is providedwith a spiral groove 131, the ends of the spiral groove terminating at,and in registry with, the inlet and outlet ports 125 and 126,respectively, when the core is received in the casing. This spiralgroove 131, cooperating with the inner sleeve member 116 of the casing,forms a spiral passage for the product being heated. Since this spiralpassage terminates at the inlet and outlet ports 125 and 126, a straightthrough passage is provided which eliminates pockets in which theproduct might be trapped and over heated.

The fianges 129 space apart the inner and outer sleeve members 128 and130 of the core to provide therebetween an enclosed heat exchangechamber 132. A fitting 133 is secured, as by welding, to the innersleeve 128`and is provided with a hole 134 for introducing a heatexchange medium, such as steam or hot water, into the heat exchangechamber 132, this fitting 133 being located near the top of the core.Another fitting 135 is secured, as by welding, to the inner sleeve 128near the bottom thereof and it communicates with the heat exchangechamber 132 for discharging the heat exchange medium therefrom. Thefittings 133 and 135, therefore, provide means for circulating a heatexchange medium through the heat exchange chamber 132.

The sleeve members 116 and 130 are relatively thin so that rapid andefficient heat exchange takes place between the heat exchange chambers118 and 132 and the spiral passage 131 located therebetween. The heatexchange chambers 118 and 132 are completely isolated from each otherand from the spiral passage 131 so that there is no danger of the heatexchange medium entering or leaking into the spiral passage containingthe product being heated. Because of the tapered surfaces on the casingand the core throughout the length of the casing and the core, a tightseal is at all times maintained therebetween which substantiallyeliminates leakage of the product from one convolution of the groove 131to the next convolution and forces the product to flow along the spiralpassage. The outer sleeve member 130 of the core is provided with anannular groove 137 near each end thereof and an O-ring 138 of resilientmaterial, such as neoprene or the like, is located in each of theseannular grooves. These O-rings 138 cooperate with the tapered innersurface 117 of the casing for positively packing the ends of the twosleeve members 116 and 139 Without in any way interfering with the tightseal between and throughout the lengths of these two sleeve members. Inthe unlikely event that leakage of the product should occur, the O-ringsprevent the product from leaking from the heat exchanger. The O-ringsprovide self-adjusting sealing means for effectively preventing anyleakage of the product being heated.

The casing of the heater 110 is vertically mounted on the supportingstand 112. In this connection, the ring 123 is secured by means of aspacer ring 140 and screws 142 to an upper platform 141 of thesupporting frame. The platform ring 141 is carried by legs 143 to whichis also secured a lower platform 144. The legs 143 may be formed ofpipes or tubes, or the like, and secured, as by welding, to the upperplatform ring 141 and the lower platform 144.

The lower platform 144 carries a motor, such as an hydraulic motor. Thebase 146 of the motor is secured to the platform 144 by means of screws147 and it carries an upwardly extending cylinder 148. A piston carriedby a piston rod 149 reciprocates in the cylinder 148. The upper end ofthe cylinder 148 is provided with a head 150 for guiding the piston rod194. The upper end of the piston rod 149 is provided with ascrewthreaded extension 151 on which is clamped a hub 152 of a spider bymeans of a nut 153. The legs 154 of the spider are secured, as byWelding, to the upper end of the inner sleeve member 128 of the core.When hydraulic pressure is applied to the motor the motor raises thecore vertically from the casing, such vertical position beingillustrated at the right of Fig. l0. When the hydraulic pressure isreleased, the core drops vertically into the casing. By reason of thisvertical movement of the core, self-alignment between the core and thecasing is assured without any tendency to cause the mating taperedsurfaces to become out of round. When the core is thus raised out of theeasing, the inner smooth tapered surface of the casing and the outergrooved tapered surface of the core are exposed so that they may bereadily cleaned.

AThe cylinder head 150 is provided with a pin 156 to be received in ahole 157 in the hub 152 of the spider when the core is received in thecasing. The pin and hole form interengaging locating means for fixingthe rotative position of the core with respect to the casing forregistering the ends of the spiral groove 131 With the inlet and outletports 125 and 126. A ring 158 is removably and longitudinally adjustablycarried by the casing by means of studs 159 secured in the ring 124 andcooperating nuts 160. When the core is received in the casing the ring158 is applied over the studs 159 and the nuts 160 are then applied tothe studs and are tightened to force the core into the casing so as toassure a tight seal between the tapered surfaces of the core and thecasing. To elevate the core above the casing, the ring 158 is firstremoved and then hydraulic pressure is applied to the motor. When thecore is so elevated, a pair of sector shaped braces 72, having holes 73,is applied to the upper end of the casing, the holes 173 accommodatingthe studs 159. These braces 172 are held in place on the studs 159 bythe nuts 160 and the inner edges of the braces 172 engage the piston rod149 for readily supporting the elevated core during cleaning operations.When it is desired to lower the core into the casing, of course, thesebraces are removed. The braces 172 are illustrated in Fig. l5 and areshown applied to the cooler 111 at the right side of Fig. 10.

The cooler 111 is illustrated in more detail in Figs. l2 and 14 and theconstruction of the cooler is substantially the same as that of theheater 110 and like reference characters have been utilized for likeparts. The essential difference between the cooler 111 and the heater110 is in the construction of the heat exchange charnbers. In thisrespect, the inner sleeve member 116 of the casing is providedexteriorly with a spiral rib 162 for forming a spiral heat exchangechamber 163. The upper end of this spiral heat exchange chamber 163terminates at and communicates with a fitting 164 through which acooling medium, such as water, may be introduced into the spiral heatexchange chamber. The lower end of the spiral heat exchange chamber 163is provided with a fitting 165 for discharging the cooling medium.

The outer surface of the inner sleeve member 128 of the core is alsoprovided with a spiral rib 171 for providing a spiral heat exchangepassage 166. The upper end of the heat exchange passage 166 terminatesin a fitting 167 for supplying a cooling medium to the heat exchangepassage. Likewise, the lower end of the heat exchange passage 166 isprovided with a fitting 168 for discharging the cooling medium from thespiral heat exchange passage 166. The product, such as milk, juices andthe like, is fed into the spiral groove 131 by means of an upper fitting169 and is discharged from the spiral groove 131 by means of a lowerfitting 178. The fittings 169 and 170 extend through the casing and openinto the tapered inner surface of the internal sleeve 116 in registrywith the ends of the spiral groove 131. The spiral groove 131 and thespiral heat exchange passages 163 and 166 all run in the same directionand, as illustrated, they are shown to be in effect in the nature ofright-hand threads. The spiral passages 163 and 166 operate to preventstratification of the cooling medium and thereby provide rapid andefficient heat transfer. The operation of the cooler, with the exceptionof the direction of heat transfer, is essentially the same as theoperation of the heater.

The cooler 111 is vertically mounted on the supporting frame 112 in thesame manner as the heater, The

vertical legs 143 of the supporting frame are connected together andbraced by transverse braces 175 which also may be made of pipes, tubesand the like, suitably welded to the vertical legs. By mounting theheater and cooler on the common supporting frame they may becooperatively associated to perform desired processes. For example, theheater may be a pasteurizer or sterilizer for pasteurizing orsterilizing milk and the cooler 111 may be utilized for cooling thepasteurized or sterilized milk. In this connection, the outlet fittingof the heater may be connected by a relatively large diameter pipe 176to the inlet fitting 169 of the cooler, this connecting pipe 176 actingas a holding valve. The connecting pipe 176 is provided with a T fitting177 having a thermometer well for receiving a temperature-responsivedevice connected to a suitable control instrument by a connection 178.The outlet fitting of the cooler may be connected by a pipe 179 to adiversion valve 180 operated by a motor 181. So long as the temperatureof the pasteurized or sterilized milk passing the fitting 177 ismaintained at the desired pasteurizing or sterilizing temperature, thethermometer controller operates the motor 181 and, hence, valve 180 topass the cooled milk through pipe 182 to a suitable bottling or canningmechanism. If, on the other hand, the temperature of the milk at the Tfitting 177 should decrease below the desired value, the motor 181 andvalve 180 are operated to divert the cooled milk through pipe 183.

Fig. 16 illustrates a casing for a heater which is lagged with thermalinsulating material. Here the heater casing is substantially the same asthe heater casing of Fig. l1 and like reference characters have beenutilized for like parts. In Fig. 16 the rings 123 and 124 are made widerand a thermal insulating material 185 is packed about the outer tubularmember 114 between the rings 123 and 124 and a suitable outer shell 186may be secured to the rings 123 and 124 for maintaining the insulatingmaterial 185 in place. The use of this insulating material provides forgreater efficiency in operation of the heater.

When the heat exchangers of this invention are utilized for heating orcooling food stuff, such as milk, fruit or vegetable juices or the like,the heaters and coolers are preferably made of non-corrosive metals,such as stainless steel or the like. This not only makes it possibleadequately to clean and sterilize the heat exchangers, but it alsoprovides a neat appearance. When the heat exchange assembly is utilizedfor pasteurizing or sterilizing milk, the milk may be forced through theheater and the cooler under pressure by the homogenizer. As a typicalexample of the use of the assembly for this purpose, the followingdimensions have proven to be very satisfactory: The cores of the heaterand cooler are substantially 20.250 inches long and have a diameter ofsubstantially 12.250 inches at the large end and 11.898 inches at thesmall end. This provides a taper of substantially 1/2 degree. In theheater the spiral groove 131 is substantially 3%; inch wide andsubstantially '0716 inch deep and the spiral groove extends along thecore for substantially 16.250 inches. The groove has 321/2 turns, whichprovides a 100 foot long groove through which milk passes at a velocityyof substantially 24 ft. per second. In the cooler the spiral groove 131is substantially 3A inch wide and 1A inch deep and it extends along thecore for substantially 17.062 inches. The spiral groove has 191/2 turnsto provide a passage length of substantially 60 feet through which themilk passes at a velocity of 10 feet per second. Both the heater and thecooler have substantially the same rate of flow of milk therethrough,being about 250 gallons per hour. The milk may be rapidly heated topasteurizing or sterilizing temperatures by the application of steam tothe heat exchange chambers 118 and 132 at normal pressures. Likewise,the milk may be rapidly cooled to suitable temperatures for bottling andcanning by supplying water to the heat exchange chambers or passages 163and 166 at usual tap water temperatures.

Reference is made to copending application Serial No. 223,482, filedApril 28, 1951, by Roy R. Graves and Edward K. Kuhles, having adisclosure corresponding to the disclosure of Figs. 9 to 16 of thisapplication. The claims of this application are directed generally tothe construction of the heat exchanger including the casing, core andclamping ring. The claims of the copending application includelimitations to the O-rings, the locating means for angularly positioningthe casing and core,

the supporting stand, and the motor means for raising the corevertically from the casing,

While for purposes of illustration several forms of this invention havebeen disclosed, other forms thereof may become apparent to those skilledin the art upon reference to this disclosure and, therefore, thisinvention is to be limited only by the scope of the appended claims.

I claim as my invention:

l. A separable heat exchanger comprising a substantially cylindricalcasing including a casing member and a separate internal sleeve membersecured adjacent its ends within the casing member and providing an enclosed annular heat exchange chamber between the casing member and theinternal sleeve member, the inner' surface of the internal sleeve memberbeing smooth and slightly and uniformly tapered throughout from end toend, a substantially cylindrical core including an external sleevemember and means for providing an enclosed heat exchange chamber withinthe external sleeve member, the outer surface of the external sleevemem` ber being slightly and uniformly tapered throughout from end to endand conforming to the taper of the internal sleeve member of the casing,said core being longitudinally removably received in the casing and thetapered surfaces of the internal sleeve member of the casing and of theexternal sleeve member of the core providing the sole means forsupporting and seating the core within the casing and providing a tightseal therebetween throughout their entire lengths when the core isreceived and pressed into the casing, a uniform spiral groove in theouter tapered surface of the external sleeve member of the core havingits ends terminating at points spaced inwardly from the ends of thetapered surface within the contines of the tapered surface and formingan enclosed continuous spiral passage between said points which issealed throughout its length and which is in heat exchange relation withthe enclosed heat exchange chambers in the casing and core when the coreis received in and pressed into the casing, an enclosed inlet portadjacent one end of the heat exchanger conimunicating directly with oneend of the spiral passage and an enclosed outlet port adjacent the otherend of the heat exchanger communicating` directly with the other end ofthe spiral passage to provide pocketless, straight through anduninterrupted flow through the ports and spiral passage, and inlet andoutlet ports adjacent the ends of the heat exchanger communicating withthe enclosed heat exchange chambers.

2. A separable heat exchanger comprising a substantially cylindricalcasing including a casing member and a separate internal sleeve membersecured adjacent its ends within the casing member and providing anenclosed annular heat exchange chamber between the casing member and theinternal sleeve member, the inner surface of the internal sleeve memberbeing smooth and slightly and uniformly tapered throughout from end toend, a substantially cylindrical core including an external sleevemember and means for providing an enclosed heat exchange chamber withinthe external sleeve member, the outer surface of the external sleevemember being slightly and uniformly tapered throughout from end to endand conforming to the taper of the internal sleeve member of the casing,said core being longitudinally removably received in the casing and thetapered surfaces of the internal sleeve member of the casing and of theexternal sleeve member of the core providing the sole means forsupporting and seating the core within the casing and providing a tightseal therebetween throughout their entire lengths when the core isreceived and pressed into the casing, a uniform spiral groove in theouter tapered surface of the external sleeve member of the core havingits ends terminating at points spaced inwardly from the ends of thetapered surface within the connes of the tapered surface and forming anenclosed continuous spiral passage between said points which is sealedthroughout its length and which is in heat exchange relation with theenclosed heat exchange chambers in the casing and core when the core isreceived in and pressed into the casing, an enclosed inlet port adjacentone end of the heat exchanger communicating directly with one end of thespiral passage and an 'enclosed outlet port adjacent the other end ofthe heat exchanger communicating directly with the other end of thespiral passage to provide pocketless, straight through and uninterruptedow through the ports and spiral passage, and inlet and outlet portsadjacent the ends of the heat exchanger communicating with the enclosedheat exchange chambers, and a ring removably and longitudinallyadjustably carried by the casing at the end thereof where the internalsleeve thereof has the largest internal diameter and engaging thecorresponding end of the core for forcibly pressing the tapered outersurface of the external sleeve of the core into tight sealing engagementwith the tapered inner surface of the internal sleeve of the casingthroughout their lengths when the core is received in the casing.

References Cited in the ile of this patent UNITED STATES PATENTS 536,354Kohl Mar. 26, 1895 1,046,298 Hurley Dec. 3, 1912 1,639,051 Munday Aug.16, 1927 1,854,619 Mortensen Apr. 19, 1932 2,445,115 Hanrahan July 12,1948 2,508,212 Ball May 16, 1950

